package io.renren.common.utils;

import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
 * @version V1.0
 * @desc AES 加密工具类
 */
public class AESUtils {

	private static final String KEY_ALGORITHM = "AES";
	private static final String DEFAULT_CIPHER_ALGORITHM = "AES/ECB/PKCS5Padding";// 默认的加密算法
	private static final String SEED = "AcQ8`Z)j!}BK&ut7";

	/**
	 * AES 加密操作
	 *
	 * @param content
	 *            待加密内容
	 * @param password
	 *            加密密码
	 * @return 返回Base64转码后的加密数据
	 */
	public static String encrypt(String content) {
		return encrypt(content, SEED);
	}

	/**
	 * AES 加密操作
	 *
	 * @param content
	 *            待加密内容
	 * @param password
	 *            加密密码
	 * @return 返回Base64转码后的加密数据
	 */
	public static String encrypt(String content, String password) {
		try {
			Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);// 创建密码器

			byte[] byteContent = content.getBytes("utf-8");

			cipher.init(Cipher.ENCRYPT_MODE, getSecretKey(password));// 初始化为加密模式的密码器

			byte[] result = cipher.doFinal(byteContent);// 加密

			return parseByte2HexStr(result);// 通过Base64转码返回
		} catch (Exception ex) {
		}

		return null;
	}

	/**
	 * AES 解密操作
	 *
	 * @param content
	 * @param password
	 * @return
	 */
	public static String decrypt(String content) {
		return decrypt(content, SEED);
	}

	/**
	 * AES 解密操作
	 *
	 * @param content
	 * @param password
	 * @return
	 */
	public static String decrypt(String content, String password) {

		try {
			// 实例化
			Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);

			// 使用密钥初始化，设置为解密模式
			cipher.init(Cipher.DECRYPT_MODE, getSecretKey(password));

			// 执行操作
			byte[] result = cipher.doFinal(parseHexStr2Byte(content));

			return new String(result, "utf-8");
		} catch (Exception ex) {
		}

		return null;
	}

	/**
	 * 生成加密秘钥
	 *
	 * @return
	 */
	private static SecretKeySpec getSecretKey(final String password) {
		// 返回生成指定算法密钥生成器的 KeyGenerator 对象
		KeyGenerator kg = null;

		try {
			kg = KeyGenerator.getInstance(KEY_ALGORITHM);

			// AES 要求密钥长度为 128
			SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
			secureRandom.setSeed(password.getBytes());
			kg.init(128, secureRandom);
			// 生成一个密钥
			SecretKey secretKey = kg.generateKey();

			return new SecretKeySpec(secretKey.getEncoded(), KEY_ALGORITHM);// 转换为AES专用密钥
		} catch (NoSuchAlgorithmException ex) {
		}

		return null;
	}

	/**
	 * 将16进制转换为二进制 解密
	 * 
	 * @param hexStr
	 * @return
	 */
	public static byte[] parseHexStr2Byte(String hexStr) {
		byte[] result = new byte[hexStr.length() / 2];
		for (int i = 0; i < hexStr.length() / 2; i++) {
			int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
			int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2), 16);
			result[i] = (byte) (high * 16 + low);
		}
		return result;
	}

	/**
	 * 将二进制转换成16进制 加密
	 * 
	 * @param buf
	 * @return
	 */
	public static String parseByte2HexStr(byte buf[]) {
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < buf.length; i++) {
			String hex = Integer.toHexString(buf[i] & 0xFF);
			if (hex.length() == 1) {
				hex = '0' + hex;
			}
			sb.append(hex);
		}
		return sb.toString();
	}
}